Diagnostic Clinical Microbiology: Two Cases of Endocarditis Caused by Streptococcus Pyogenes

Running head: DIAGNOSTIC CLINICAL MICROBIOLOGY
DIAGNOSTIC CLINICAL MICROBIOLOGY
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DIAGNOSTIC CLINICAL MICROBIOLOGY
Introduction
The prevalence of infective endocarditis (IE) is a rare condition that is diagnosed in
children. The Group A beta-hemolytic Streptococcus pyogenes however are responsible for
causing various types of infections with various severity of infections in childhood which
might invasive along with immune-mediated disease and toxin-mediated (Esposito et al.,
2016). This paper aims to present two cases of endocarditis caused by S. pyogenes and
additionally discuss the diagnostic approaches and treatment along with prognosis of the
disease caused in the respective cases.
Case 1:
Patient’s history
The case reveals the health condition of an unvaccinated Caucasian female who was
admitted to the rural Emergency Department. The patient had a history of fever along with a
three day of history of lethargy along with reduced oral uptake and showed erythematous
rash. Even after discharge from ED, the patient showed fever along with signs of sepsis. This
required her to be shifted to the ICU where she was being provided with fluid rehydration and
one dose of ceftriaxone was administered. The family history of the patient showed that out
of 6 of her siblings, at least 3 suffered from pharyngitis.
Different diagnostic approaches
The patient when diagnosed by the physician was mentioned to have a streptococcus
infection of the throat. During the examination the patient showed to have systolic murmur
along with purple nodules of the fingers and toes that are painfu, and erythema of the palms
and soles. The condition of the patient was hypotensive therefore she required infusions of
dopamine and epinephrine in order to maintain her blood pressure. The white blood count of

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DIAGNOSTIC CLINICAL MICROBIOLOGY
the patient was seen to be 18.7×109 /L with 73% neutrophils. ECG was also conducted,
reports of which was normal. Additionally echocardiogram was done which showed a mass
that is mobile on the posterior mitral leaflet (0.7 cm × 0.5 cm) along with a small atrial septal
defect (ASD)/patent foramen ovale (PFO). Additionally computed tomography (CT) showed
that multiple bilateral asymmetric hypoattenuating foci. There was cardiac monitoring that
showed abnormalities and along with it there was a prompt repeat of ECG. This showed
accelerated junctional rhythm and atrioventricular (AV) dissociation Blood cultures were
drawn from the patient which showed positive results for Streptococcus pyogenes.
Treatments and prognosis
After the client tested positive for streptococcus pyogenes, treatment was initiated.
The antimicrobial of choice in the case study was penicillin. Other drugs that were used
include clindamycin, vancomycin and meropenem though the latter drugs were discontinued
after a short time. Penicillin is known to be a very effective antimicrobial if treatment is
initiated promptly. Penicillin acts by inhibiting the action of the enzyme Trans peptidase
which usually catalyze the final step in the cell wall biosynthesis and the cross-linking of
peptidoglycan (Singh & Ganjoo, 2017). The streptococcus pyogenes is a gram positive
bacteria and this means that it has a thick layer of the peptidoglycan that penicillin inhibits
cross-linking and this is why it was selected. The signs and symptoms improved after only a
short time of medication in the case study. In the case study, other drugs were also used and
they include meropenem and vancomycin though they were discontinued after a short time.
The rationale as to why they were used was to treat some strains of streptococcus that could
be resistant to penicillin (Weidman, Al-Hashami, & Morris, 2014). This is why they were
discontinued after the child or the patient responded well to penicillin. Prognosis can be
defined as the response to medication (Tseng et al., 2014). In this case study the prognosis for
the condition has been the portal of entry which is likely to be pharyngitis. Additionally there